Polyamide resins, which are superior for example in mechanical properties and heat resistance, have been used widely in various fields such as of electric and electronic devices, automobile, machinery, construction material and others. Recently, in the tread toward substitution of metal with resin, there is an increasing demand for a resin material having the strength and rigidity equivalent to those of metal materials. In particular, a high level of flame retardancy is required to electrical components such as connectors and home appliances including housing materials for electrical apparatuses presented by OA devices such as portable personal computer, word processor, electronic dictionary and cellphone. Generally, a method of adding a halogen- or triazine-based flame retardant or a method of depositing Mg on resin has been used to make the resin flame-retardant. Unfavorably, halogen-based flame retardants are considered to have adverse effects on environment and human, for example with the highly corrosive halogen-based gases and hazardous substances generated during combustion, and thus there is a movement toward restriction on use of the halogen-based flame retardants.
Accordingly, halogen-free triazine-based flame retardants attracted attention and there are many studies on these retardants. It is possible for moldings containing no reinforcing material to satisfy the requirements in flame retardancy corresponding to the UL94 V-0 specification at a thickness of 1/32 inch, but unfavorably, it is not possible for moldings reinforced with glass fiber or the like, to satisfy the UL94 V-0 specification because of cotton ignition, even if a flame retardant is blended in a great amount.
On the other hand, a flame-retarding method of using an intumescent flame retardant such as melamine phosphate, melamine pyrophosphate or melamine polyphosphate in a glass fiber-reinforced polyamide resin was proposed, but for satisfaction of the requirements of UL94 V-0 specification at a thickness of 1/32 inch, it was still needed to blend the melamine phosphate-based flame retardant in a great amount, possibly leading to deterioration in mechanical properties such as toughness and electrical properties such as tracking resistance, and thus the method was still practically far from satisfactory.
Alternatively, a method of using a phosphinate and a (reaction product of melamine and phosphoric acid) in combination (see, for example, Patent Document 1) and a method of using a phosphinate, a (reaction product of melamine and phosphoric acid) and a metal compound in combination (see, for example, Patent Document 2) were proposed, and the moldings obtained by these methods are known to satisfy the requirements in flame retardancy for molded articles of 1/16 inch in thickness by the UL94 V-0 specification. It is possible to reduce the amount of the flame retardant by these methods and thus to improve the mechanical properties (in particular, toughness such as bending deflection) and the electrical properties (tracking resistance) of the resulting moldings. However, when an inorganic filler is added in an amount of 40% or more for improvement in mechanical properties such as impact resistance, the content of the resin declines and thus the running properties at extrusion declines significantly, even if two or more flame retardants are blended, and for that reason, it was very difficult to produce a high-rigidity material that demands an inorganic filler at a high blending ratio. In addition, these compositions, which contain a highly flammable fatty acid metal salt, are still uncertain of their flame retardancy and far from satisfactory when used for improvement of flowability, release characteristics and others during molding.
In addition, very high rigidity and flame retardancy as well as favorable appearance are demanded for housing materials for electrical apparatuses represented by OA devices such as portable personal computer and word processor, and the reinforcing materials based on conventional technology are unfavorably exposed on the surface of the molded article during molding, causing waviness on the surface of the molded article and deterioration in appearance.    Patent Document 1: JP-A 2004-263188    Patent Document 2: JP-A 2007-23206